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USB: keep count of unsuspended children

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This patch (as818b) simplifies autosuspend processing by keeping track
of the number of unsuspended children of each USB hub.  This will
permit us to avoid a good deal of unnecessary work all the time; we
will no longer have to create a bunch of workqueue entries to carry
out autosuspend requests, only to have them fail because one of the
hub's children isn't suspended.

The basic idea is simple.  There already is a usage counter in the
usb_device structure for preventing autosuspends.  The patch just
increments that counter for every unsuspended child.  There's only one
tricky part: When a device disconnects we need to remember whether it
was suspended at the time (leave the counter alone) or not (decrement
the counter).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2006-11-22 16:55:54 -05:00 • committed by Greg Kroah-Hartman
parent d25450c687
commit ee49fb5dc8
3 changed files with 38 additions and 11 deletions
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14
drivers/usb/core/hub.c
View file

@ -1039,6 +1039,8 @@ static void recursively_mark_NOTATTACHED(struct usb_device *udev)
if (udev->children[i])
recursively_mark_NOTATTACHED(udev->children[i]);
}
if (udev->state == USB_STATE_SUSPENDED)
udev->discon_suspended = 1;
udev->state = USB_STATE_NOTATTACHED;
}
@ -1228,6 +1230,14 @@ void usb_disconnect(struct usb_device **pdev)
*pdev = NULL;
spin_unlock_irq(&device_state_lock);
/* Decrement the parent's count of unsuspended children */
if (udev->parent) {
usb_pm_lock(udev);
if (!udev->discon_suspended)
usb_autosuspend_device(udev->parent, 1);
usb_pm_unlock(udev);
}
put_device(&udev->dev);
}
@ -1356,6 +1366,10 @@ static int __usb_new_device(void *void_data)
goto fail;
}
/* Increment the parent's count of unsuspended children */
if (udev->parent)
usb_autoresume_device(udev->parent, 1);
exit:
module_put(THIS_MODULE);
return err;